1. Field of the Invention
This invention relates to an automatic focusing camera having an automatic exposure locking function.
2. Description of the Related Art
An automatic focusing (hereinafter referred to as AF) camera which is arranged to have a photometric value locked for an automatic exposure (hereinafter referred to as AE) after completion of AF adjustment and to readily lock the automatic exposure to a specific object by a single process of operation has been disclosed in Japanese patent application Laid-Open No. SHO 58-120225. Meanwhile, many patent applications have been filed, including U.S. Pat. No. 4,429,974, for cameras which are of the kind performing photometric and computing actions together with a displaying action when a shutter button is pushed down to its first stroke position and are arranged to have the photometric, computing and displaying actions allowed to continue by means of a timer arrangement (hereinafter referred to as photometric timer function). The camera with the photometric timer function, however, has the following shortcoming: If an AE lock function remains operative after an AF lock action during the photometric timer period, it is impossible to obtain a photometric value for any object that is other than a main object. This presents a problem, because:
In photographing under ordinary conditions, an apposite exposure is generally attainable from a photometric value obtained at the time of focusing. However, in the event of an object having extremely varied degrees of luminance, it would become impossible to make an apposite exposure as desired on the basis of a photometric value which is obtained through the process of focusing and is held in store, if the object moves or if the luminance thereof changes. It is therefore necessary, for an exposure which is highly apposite to the intention of the photographer, to take into consideration some additional photometric value that is obtained for objects other than the main object. However, if light measurement in real time is impossible during the photometric timer period like in the case of cameras of the above stated kind, it is hardly possible to find the luminance of different objects existing within a picture plane by variously changing the composition of a picture. The photographer is then at a loss to know whether an exposure first determined is good or requires some correction. The conventional cameras having the photometric timer function thus put the photographer to great inconvenience.